1. Field of the Invention
The present invention is directed to a cable stripping tool for stripping insulation from the conductor core at the end of or midspan in an electric power cable.
2. Description of Related Art
Termination of a power cable involves stripping the outer jacket and insulation from the conductor core. There are many different combinations of primary and secondary cable sizes—creating a need for an installer to be able to prepare numerous cable sizes based on application needs, cable manufacturer and regional code requirements, and company specific installation instructions.
Some tools are built for application-specific purposes. They have one blade setting and one bore size specific to the cable geometry. These tools are narrowed in usability and not conducive to working across a range of sizes.
Other preparation tools are more flexible and utilize interchangeable bushings to allow the same basic tool frame to work across a range of application needs. Specifically sized bushings are used for different cable sizes within the same tool frame. Every time a worker changes to a different application, they must change the bushing in their tool. This can be time consuming and cause delays if the correct bushing is not available. Typically, tools utilizing interchangeable bushings are only used for end stripping applications. A different tool must be used for midspan access, which further complicates the range of tools the end user must utilize for a full range of cable preparation.
Adjustable tools as opposed to bushing/fixed tool designs are based on a configurable platform to accommodate different cable diameters and insulation thicknesses with one tool. These designs have a limitation on cable diameter range and tend to require more than one jaw size as the end user transitions from smaller to larger cable sizes. The blade depth is limited as the cable diameter changes.
Tools on the market may incorporate a V-jaw A that is 180° from a blade B, as shown by example in the provided FIGS. 1 and 2A-2B of the prior art in which a minimum cable diameter Cmin and maximum cable diameter Cmax are shown. In these tools, as the cable diameter changes, the relative contact point between the blade and the cable changes, resulting in variable cutting action and depth, and requiring adjustment of the blade set as shown by difference D (FIG. 2A).
Another limitation with existing tools having V-jaws is that the reaction force created as the blade cuts through the cable is not directly supported, such reaction force F being further exemplified in FIGS. 2A-2B of the prior art. Instead, reaction force F has components from the angle support causing cable shifting from the blade, resulting in an unstable cut. In FIG. 2A, the reaction force F is shown as existing on the side of the cable, such reaction force created by the contact point of the blade pushing against the cable during the stripping process. FIG. 2B is a closer view of the interaction in FIG. 2A, demonstrating the cable's shift out of the V-jaw A once blade B begins the cutting sequence. The cable also loses its proper alignment within the V-jaw.
On the V-jaw design, the clamping force must be higher to keep the cable positioned in the tool as demonstrated in FIGS. 2A-2B. The resulting rotational friction of the cut is increased. Higher clamping force equates to higher friction and poorer tool stability, making it harder to perform the stripping operation. Often, the adjustable platform needs to be repositioned during the cut to re-establish the clamping force on the cable, or the jaw must be retightened during the cut since the set-up becomes unstable and loosens when trying to make aggressive cuts. The resulting performance of the tool is unstable and difficult to keep the blade tracking in a consistent direction relative to the cable. This results in poor cut quality. Unintentional damage to the conductor core may also result. Since the V-jaw will not work across a wide range of diameters, the tool needs to be changed to a larger V-Jaw as the cable diameter increases.
Many tools on the market also utilize a fixed blade tracking (feed) angle, requiring an external supporting stop at the end of cut to get a clean square cut.